It seems that your dreams of seeing the Scouting Legion and Titans in real-life action are at hand. With the recent announcement made in Japan last April 2nd, it has been revealed who their Eren will be. Haruma Miura, famously known as Shota Kazehaya in another live-action, Kimi no Todoke movie and voice of Yama in the previous year's move Space Pirate Captain Harlock, will be taking the lead in killing titans.
Further casting and details about this live-action is yet to be confirmed, but, their shooting areas have been said to be in Hashima Islan, Nagasaki, to put the destroyed world of Shingeki no Kyojin to life. This land is also known for photo shoot location and under the name Gunkanjima. We can expect that the movie will be based on the manga with a little modifications under the supervision of the manga's author, Hajime Isoyama.
